Barrier pressure and muscle relaxants

The effects of pancuronium and vecuronium on the lower oesophageal sphincter pressure were studied in 24 healthy patients anaesthetised with 0.5% halothane in nitrous oxide and oxygen. Following pancuronium 0.1 mg/kg intravenously, there was a significant increase in barrier pressure from a control value of 2.0 (SEM 0.14) kPa to 3.0 (SEM 0.27) kPa 1 minute after injection (p less than 0.05). This increase was sustained throughout the 15 minute period of recording and was accompanied by a significant increase in heart rate (p less than 0.001). Following administration of vecuronium 0.1 mg/kg intravenously there was an initial modest, though not significant increase in barrier pressure. This increase was significant (p less than 0.05) at 15 minutes. There were no cardiovascular changes following vecuronium.